The present invention relates to methods and devices for removing tissue samples, and more specifically to improved instruments and methods for acquiring soft body tissue.
It is often desirable and frequently necessary to sample or remove a portion of tissue from humans and other animals, particularly in the diagnosis and treatment of patients with cancerous tumors, pre-malignant conditions, and other diseases or disorders.
Typically, in the case of cancer, particularly cancer of the breast, there is a great emphasis on early detection and diagnosis through the use of screening modalities, such as physical examination, and particularly mammography, which is capable of detecting very small abnormalities, often nonpalpable. When the physician establishes by means of a mammogram or other screening modality, such as ultrasound, that suspicious circumstances exist, a biopsy must be performed to capture tissue for a definitive diagnosis as to whether the suspicious lesion is cancerous. Biopsy may be done by an open or percutaneous technique. Open biopsy, which is an invasive surgical procedure using a scalpel and involving direct vision of the target area, removes the entire mass (excisional biopsy) or a part of the mass (incisional biopsy). Percutaneous biopsy, on the other hand, is usually done with a needle-like instrument through a relatively small incision, blindly or with the aid of an artificial imaging device, and may be either a fine needle aspiration (FNA) or a core biopsy. In FNA biopsy, individual cells or clusters of cells are obtained for cytologic examination and may be prepared such as in a Papanicolaou smear. In core biopsy, as the term suggests, a core or fragment of tissue is obtained for histologic examination which may be done via a frozen section or paraffin section.
The type of biopsy utilized depends in large part on circumstances present with respect to the patient, including the location of the lesion(s) within the body, and no single procedure is ideal for all cases. However, core biopsy is extremely useful in a number of conditions and is being used more frequently by the medical profession.
A very successful type of image guided percutaneous core breast biopsy instrument currently available is a vacuum-assisted automatic core biopsy device. One such successful biopsy device is shown and disclosed in U.S. Pat. No. 5,526,822 to Burbank et al, expressly incorporated by reference herein. This device, known commercially as the MAMMOTOME(copyright) Biopsy System, which is available from Ethicon Endo-Surgery, Inc., a division of Johnson and Johnson, has the capability to actively capture tissue prior to cutting the tissue. Active capture allows for sampling through non-homogeneous tissues. The device is comprised of a disposable probe, a motorized drive unit, and an integrated vacuum source. The probe is made of stainless steel and molded plastic and is designed for collection of multiple tissue samples with a single insertion of the probe into the breast. The tip of the probe is configured with a laterally disposed sampling notch for capturing tissue samples. Orientation of the sample notch is directed by the physician, who uses a thumbwheel to direct tissue sampling in any direction about the circumference of the probe. A hollow cylindrical cutter severs and transports tissue samples to a tissue collection chamber for later testing.
While this type of system functions very well as a core biopsy device, there are occasions when it may be useful to have the capability of acquiring a relatively large intact tissue sample. One such core biopsy device is disclosed in U.S. Pat. No. 5,111,828, to Kornberg et al., also expressly incorporated by reference herein. In the device disclosed by Kornberg et al., the tissue receiving port is disposed at the distal end of the device and is oriented axially rather than laterally. A disadvantage of this type of device, however, is the inability to acquire a tissue sample having a cross-section larger than that of the cannula through which the sample will be removed. Additionally, it is difficult, using such a device, which obtains cylindrical shaped specimens, to determine whether an entire lesion of interest is being removed or whether a further procedure will be necessary. This is particularly true because most lesions of interest are typically spherical in shape, having a diameter of approximately 1 cm. The only way one can tell whether the entire lesion has been removed using the Kornberg technique is to remove and examine the specimen, determining whether each of the margins of the specimen is xe2x80x9ccleanxe2x80x9d, meaning that there is no evidence of lesion, or xe2x80x9cdirtyxe2x80x9d, meaning that lesion is evident right to the edge of the specimen. Of course, if one or more specimen margins is xe2x80x9cdirtyxe2x80x9d, it is almost a certainty that a portion of the lesion remains in the patient, and if the biopsy test results on the lesion are positive, a further surgical procedure will be indicated.
It would be desirable, therefore, to have an apparatus and method for isolating a target lesion, with a sufficient border around and beyond the lesion that the likelihood of xe2x80x9ccleanxe2x80x9d margins is relatively high. It would further be advantageous to have an apparatus and method available for initially isolating the entire target lesion, by cutting a swath completely about the lesion to cut off its blood supply, after which a further procedure is undertaken to remove it from the patient""s body. This approach would help to minimize the migration of possibly cancerous cells from the lesion to surrounding tissue or bloodstream during the removal procedure.
The present invention addresses the foregoing problems by providing such an apparatus and method for precisely isolating a target lesion, resulting in a high likelihood of xe2x80x9ccleanxe2x80x9d margins. This advantageously will often result in the ability to both diagnose and treat a malignant lesion with only a single percutaneous procedure, with no follow-up percutaneous or surgical procedure required, while minimizing the risk of migration of possibly cancerous cells from the lesion to surrounding tissue or the bloodstream.
More particularly, in one aspect of the invention, a biopsy instrument is provided for retrieving body tissue, which instrument has a longitudinal axis. The instrument comprises a distal end adapted for entry into a patient""s body, a shaft disposed along the axis, and a cutting element disposed along the shaft. The cutting element is actuatable between a radially retracted position and a radially extended position. Advantageously, the instrument is rotatable about its axis in the radially extended position to isolate a desired tissue specimen from surrounding tissue by defining a peripheral margin about the tissue specimen. Once the tissue specimen is isolated, it may be segmented by further manipulation of the cutting element, after which the tissue segments are preferably individually removed from the patient""s body through a cannula or the like. Alternatively, the specimen may be encapsulated and removed as an intact piece.
In another aspect of the invention, an instrument is provided for retrieving body tissue, having a longitudinal axis and comprising a distal end adapted for entry into a patient""s body. The instrument further comprises an element for encapsulating a tissue specimen so that it may be withdrawn as a single unit from the patient""s body. The encapsulating element preferably comprises a plurality of bands disposed along the instrument axis, each of which are actuatable between a radially retracted position and a radially extended position.
In yet another aspect of the invention, a method is disclosed for retrieving a tissue specimen from a patient""s body, comprising the steps of inserting an instrument having a distal end, a longitudinal axis, and an axially disposed cutting element, into the patient""s body, so that a distal end is disposed in a tissue region from which the tissue specimen is to be taken. The cutting element is radially expanded so that a portion thereof is radially outwardly spaced from the axis of the instrument. Once the cutting element is radially expanded, it is rotated about the axis to cut the tissue and create a peripheral boundary about the tissue specimen, to isolate the tissue specimen from surrounding tissue in the tissue region.